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"But I reject the false choice between securing this nation and wasting billions of taxpayer dollars. And in this time of great challenges, I recognize the real choice between investments that are designed to keep the American people safe and those that are designed to make a defense contractor rich," he said.

The president noted that the Government Accountability Office last year looked into 95 major defense projects and found cost overruns that totaled $295 billion.

The president said wasteful spending has many sources, including investments in unproven technologies, a lack of oversight and no-bid contracts.

"We need to invest in technologies that are proven and cost effective. We need more competition for contracts and more oversight as they are carried out," he said. "If the system isn't ready to be developed, we shouldn't pour resources into it. And if a system is plagued by cost overruns, it should be reformed. No more excuses, no more delays. The days of giving defense contractors a blank check are over."

The president said his administration is taking immediate steps to overhaul government contracting.

Starting Wednesday, his budget director is working with Cabinet officials and agency heads to develop "tough, new guidance" for federal contracts by the start of the next fiscal year on October 1.

Obama urged a reduction of outsourcing services that the federal government should perform itself, and vowed to strengthen oversight, transparency and accountability.

"I can promise you that this is just the beginning of a new way of doing business here in Washington, because the American people have every right to expect and to demand a government that is more efficient, more accountable and more responsible in keeping the public's trust," he said.

The president said his plan has broad, bipartisan support. He was joined Wednesday by Sens. John McCain, R-Arizona; Carl Levin, D-Michigan; and Claire McCaskill, D-Missouri; and Reps. Edolphus Towns, D-New York, and Peter Welch, D-Vermont.